First off, even the biggest fish (and actually more often the biggest fish) have great runs like that. What separates the big fish from the good players though is that the good players build the huge stack and walk away with all of it, and the big fish lose it all. As for playing styles at higher stakes, when i first moved up i made the mistake of thinking it was different from low stakes, when really it isn't. I play 600nl and i still pretty much play a tagg game. If i have a read that i can take someone off a hand then i do so, but i did that at lower stakes too. For bankroll management i like to have 30 buyins. Its not as if i'm ever going to have a 25 buyin downswing (if you lose 25 buyins its not cause of a downswing) but it provides me with a buffer, because busting at higher stakes hsa much higher consequences then busting at 50nl.